What Makes The Lub Dub Sound In The Heart Jun 2026

closing of the heart's four valves as they ensure blood flows in the correct direction. While often thought to be the sound of the heart muscle contracting, it is actually the result of valves snapping shut and the subsequent vibrations in the blood and heart structures. Better Health Channel +3 The "Lub" (S1) The first sound, "lub" (scientifically known as S1), is lower-pitched and lasts slightly longer. Liv Hospital +1 Anatomy: It is caused by the simultaneous closure of the